In recent years, the amount of information that is being handled by storage apparatuses is increasing dramatically. And in order to realize the redundancy of data, the storage systems of storage apparatuses are also being configured in RAID. Thus, the memory capacity of storage apparatuses is also increasing dramatically to terabyte levels, and consequently the number of disk drives that are mounted on a storage apparatus is also ever-increasing. Pursuant to the increase in the number of disk drives that are mounted, the power consumption of storage apparatuses is also increasing, and demands for realizing the power saving of storage apparatuses are growing.
Conventionally, storage apparatuses consumed wasteful power as a result of constantly setting the disk drives in a ready status regardless of the usage status of the mounted hard disk devices. In light of this, Japanese Patent Laid-Open Publication No. 2000-293314 discloses turning off the power of disk drives that were not accessed for a given period of time. However, this power saving technology has a problem in that much time is required for the start-up of a disk drive when such disk drive, in which the power was turned off, is accessed.
Thus, in order to overcome this problem, a storage apparatus has been proposed for achieving power saving while maintaining the access performance to disk devices by managing the power source of the disk devices according to a schedule (Japanese Patent Laid-Open Publication No. 2008-112293).
In addition, there is also a system of achieving both the performance and power saving of a storage apparatus by the storage apparatus receiving a notice on the usage status of the logical units from the host system, and changing the power saving status of the disk drives according to the status of the logical units (Japanese Patent Laid-Open Publication No. 2008-250506).